If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#61
|
|||
|
|||
Anybody that thinks the D70 is not *fast*..
Not sure exactly what you're saying here. Where do you come up with 1/250?
Nikon's site says: flash synchronization at up to 1/500 second Tom "E. Magnuson" wrote in message . .. On 2004-07-16, Mark M wrote: "E. Magnuson" wrote in message om... Do you happen to have a link to more info on this? Nikon specifies that it's a combined electronic/mechanical shutter. If you think about it, this is pretty much how it has to work. (Well, you could always use the electronic shutter if you always fire the mechanical shutter for a tiny bit longer than the actual exposure time.) It works just like flash sync. Here is a site that repeats what I said: http://www.jjmehta.com/indepth/nikon_d70_04.htm Thom mentions this in his review (http://www.bythom.com/D70REVIEW.HTM) but puts the boundary at 1/250. I think he's wrong because a mechanical shutter that can sync at 1/250 is a more expensive part than Nikon used in the D100 -- which was only 1/180. And there is no reason at all for a faster mechanical shutter for a 3FPS camera with an electronic shutter. I'm not saying it isn't so, but I find it interesting and would like to look further. There were some writeups on the original Canon 1D which also has a combined mechanical/electronic shutter, nothing realy detailed. -- Erik |
#62
|
|||
|
|||
Misunderstands about how a CCD works.
On 2004-07-16, Jeremy Nixon wrote:
Right -- I'm thinking of a mode that finds the highlights and puts them just under the point where they would be blown out, The problem with this is that you would need an exposure sensor that is exactly the same size (and maybe resolution) as the imaging sensor. Well, you say, why not use the sensor itself? You can (and that's how a lot non-SLR cameras work -- well for speed reasons they almost always read only a limited subset of the pixels). The main problem is that for a CCD, reading a cell's charge value is destructive. If you read it out and decide it's not long enough, you can't put the charge "back". You could read a scene, make an estimate of when it might blow out what you've seen so far, and then make the exposure, but all that reading/estimating is one of the reasons for the long "pre-shutter" lag on these cameras. (The CCD is also used for focusing.) -- Erik |
#63
|
|||
|
|||
Misunderstands about how a CCD works.
In article ,
E. Magnuson wrote: On 2004-07-16, Jeremy Nixon wrote: Right -- I'm thinking of a mode that finds the highlights and puts them just under the point where they would be blown out, The problem with this is that you would need an exposure sensor that is exactly the same size (and maybe resolution) as the imaging sensor. Only if you're being utterly pedantic about every last pixel. I for one would be happy for this sort of algorithm to be applied to the output from existing matrix metering systems. As it is, the way they actually decide what the exposure is going to be is not easilly derived from what they're seeing, and this makes them useless if you're trying to meter for the highlights. |
#64
|
|||
|
|||
Misunderstands about how a CCD works.
In article ,
E. Magnuson wrote: On 2004-07-16, Jeremy Nixon wrote: Right -- I'm thinking of a mode that finds the highlights and puts them just under the point where they would be blown out, The problem with this is that you would need an exposure sensor that is exactly the same size (and maybe resolution) as the imaging sensor. Only if you're being utterly pedantic about every last pixel. I for one would be happy for this sort of algorithm to be applied to the output from existing matrix metering systems. As it is, the way they actually decide what the exposure is going to be is not easilly derived from what they're seeing, and this makes them useless if you're trying to meter for the highlights. |
#65
|
|||
|
|||
Anybody that thinks the D70 is not *fast*..
On 2004-07-17, Tom Scales wrote:
Not sure exactly what you're saying here. Where do you come up with 1/250? Let me try again: The D70 has a hybrid mechanical/CCD electronic shutter. Slow shutter speeds are controlled by the mechanical two-curtain focal plane shutter (just like almost every other SLR). Fast shutter speeds are controlled by the CCD. However, just as with electronic flash, you must open the mechanical shutter such that it completely exposes the entire CCD before you can use it's shuttering capability. (At fast speeds, the mechanical shutter releases the second curtain before the 1st has completed - thus the exposure is via a moving slit.) So the question is what is the fastest mechanical shutter speed where the CCD is completely exposed? On the D100 it was 1/180th. On a N75 film body, it's 1/90th. Generally speaking, a faster (mechanical) sync speed is more expensive. The question I was attempting to answer was about the speed that the mechanical shutter operates on the D70. (BTW, adding to the confusion, note that sometimes an electronically timed mechanical shutter is called an "electronic" shutter - as opposed to a purely mechanical clockwork controlled shutter. These days almost all SLR shutters are electronically timed.) Nikon's site says: flash synchronization at up to 1/500 second Yes. This is achieved via the CCD electronic shutter. In theory this number could be even higher. However, many flashes have a maximum flash duration of about 1/700th of a second. If your shutter speed is higher than your flash duration, you will loose flash brightness. -- Erik |
#66
|
|||
|
|||
Anybody that thinks the D70 is not *fast*..
On 2004-07-17, Tom Scales wrote:
Not sure exactly what you're saying here. Where do you come up with 1/250? Let me try again: The D70 has a hybrid mechanical/CCD electronic shutter. Slow shutter speeds are controlled by the mechanical two-curtain focal plane shutter (just like almost every other SLR). Fast shutter speeds are controlled by the CCD. However, just as with electronic flash, you must open the mechanical shutter such that it completely exposes the entire CCD before you can use it's shuttering capability. (At fast speeds, the mechanical shutter releases the second curtain before the 1st has completed - thus the exposure is via a moving slit.) So the question is what is the fastest mechanical shutter speed where the CCD is completely exposed? On the D100 it was 1/180th. On a N75 film body, it's 1/90th. Generally speaking, a faster (mechanical) sync speed is more expensive. The question I was attempting to answer was about the speed that the mechanical shutter operates on the D70. (BTW, adding to the confusion, note that sometimes an electronically timed mechanical shutter is called an "electronic" shutter - as opposed to a purely mechanical clockwork controlled shutter. These days almost all SLR shutters are electronically timed.) Nikon's site says: flash synchronization at up to 1/500 second Yes. This is achieved via the CCD electronic shutter. In theory this number could be even higher. However, many flashes have a maximum flash duration of about 1/700th of a second. If your shutter speed is higher than your flash duration, you will loose flash brightness. -- Erik |
Thread Tools | |
Display Modes | |
|
|